from django.http import HttpResponse, Http404, HttpResponseRedirect
from django.shortcuts import render, get_object_or_404
from django.urls import reverse
from django.views import generic
from polls.models import Question, Choice


class IndexView(generic.ListView):
    template_name = 'polls/index.html'
    context_object_name = 'latest_question_list'

    def get_queryset(self):
        """Return the last five published questions."""
        return Question.objects.order_by('-pub_date')[:5]


class DetailView(generic.DetailView):
    model = Question
    template_name = 'polls/detail.html'


class ResultsView(generic.DetailView):
    model = Question
    template_name = 'polls/results.html'
# def index(request):
#     return HttpResponse("Hello, world. You're at the polls index.")

# def detail(request,question_id):
#     question = get_object_or_404(Question, pk=question_id)
#     return render(request, 'polls/detail.html', {'question': question})
    # try:
    #     question = Question.objects.get(pk=question_id)
    # except Question.DoesNotExist:
    #     raise Http404("Question does not exist")
    # return render(request, 'polls/detail.html', {'question': question})
    # return HttpResponse('You are looking at question %s'%question_id )

# def result(request,question_id):
#     response = 'You are looking at question %s'
#     return HttpResponse(response%question_id)

def vote(request,question_id):
    # return HttpResponse('You are looking at question %s'%question_id)
    question = get_object_or_404(Question, pk=question_id)
    try:
        selected_choice = question.choice_set.get(pk=request.POST['choice'])
    except (KeyError, Choice.DoesNotExist):
        # Redisplay the question voting form.
        return render(request, 'polls/detail.html', {
            'question': question,
            'error_message': "You didn't select a choice.",
        })
    else:
        selected_choice.votes += 1
        selected_choice.save()
        # Always return an HttpResponseRedirect after successfully dealing
        # with POST data. This prevents data from being posted twice if a
        # user hits the Back button.
        return HttpResponseRedirect(reverse('polls:results', args=(question.id,)))

# def index(request):
    # latest_question_list = Question.objects.order_by('-pub_date')[:5]
    # template = loader.get_template('polls/index.html')
    # context = {
    #     'latest_question_list': latest_question_list,
    # }
    # return HttpResponse(template.render(context, request))

    # latest_question_list = Question.objects.order_by('-pub_date')[:5]
    # context = {'latest_question_list': latest_question_list}

#     '''
#     一个快捷函数： render()
# 「载入模板，填充上下文，再返回由它生成的 HttpResponse 对象」
# 是一个非常常用的操作流程。于是 Django 提供了一个快捷函数，我们用它来重写 index() 视图：
#     '''
#     return render(request, 'polls/index.html', context)